Process and apparatus for distilling oil



Dec. 8, 1931. R. T. POLLOCK PROCESS AND APPARATUS FOR DISTILLING OIL Fill/ed Dec.

Patented Dec. 8, 1931 PATENT OFFICE v ROBERT T. POLLOCK, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO UNIVERSAL OIL PRODUCTS COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF SOUTH DAKOTA PROCESS AN D APPARATUS FOR DISTILLING OIL Application filed December 20, 1920. Serial No. 431,839.

This invention relates to improvements in a process and apparatus for distilling oils and refers more particularly to a process which combines the cracking of comparative- 1y heavy hydrocarbons and the topping of heavy oils simultaneously in the same process. Among the salient objects of the invention are to provide a process in which crude oil is introduced to assist in the rectification m of the oil vapors which have been released in the reaction or cracking zone, thereby absorbing enough heat to be sufficiently topped to yield considerable distillate; t provide a process in which the temperature in the is rectifier may be accurately regulated by a flow of cooling medium, such as crude oil and the conditions of temperature so controlled that the cooling medium may be topped with a simultaneous rectification of the cracked 2e oil vapors; to provide a process in which reflux condensate from the dephlegmator may be redirected to the cracking tubes to be retreated and one in which provision is made for introducing raw oil, such as gas oil or 2 fuel oil, from an an extraneous source to the dephlegmator to be commingled with and assist in the rectification of the vapor and combining with the condensate to be treated in the cracking zone; to provide a process whereby the heavier oil fractions, which are the resultant product from the topping stage, may, if desired, be run through the cracking system and one in which the lighter fractions topped from the crude may be also run through the cracking system whereby a more uniform product will result; to provide a process which is economical in operation in that a greater part of the generated heat is utilized in the conversion of the oil introduced to the system and'one that offers the possibilitv of accurate control so that the resultant product may be of a very uniform character; to provide a process which is preferably operated continuously and one thatfurnishes a means for rectifying the vapors both byintimate contact with the oil and by conduction to a cooler mediumcirculated thereabouts; to provide an apparatus for effooting this process, and, in general, to prosame to a heavily insulated expansion chamvide a process and apparatus of the character referred to. t

The single figure is a diagrammatic side elevation of the apparatus.

Referring to the drawingat 1 are crackn ing or heating tubes mounted above the furnace 2 heated by a gas burner 3 connected to a vertical reaction chamber t by a line 5 in which is interposed a valve 6. The reaction chamber in turn is connected to the dephlegmator 7 by men us of the vapor line 8 regulated by aevalve 9. This dephlegmator is shown of the multi-whirl type. The vapors introduced from the expansion chamber are directed by the baflie member 10 in a spiral course about the vertical tubes 11 which communicate between the upper and lower enlarged chambers 12 and 13. Crude oil from any convenient source may be introduced to this upper enlarged chamber 12 through the line 14 regulated by a valve 15 and flows through the vertical tubes to the iower chamber 13 from which it is withdrawn through the pipe 16 regulated by a valve 17 which directs the her 18 in which the oil, which has absorbed heat from the vapors in the dephlegmator, is permitted to vaporize, the vapors passing off through the vapor line 19 regulated by a valve 20. The vapors released from the expansion chamber 18 are dephlegmated in the aerial condenser 21 and pass over through a line 22 to a water condenser 23 where after condensation they are collected in the receiver 24. This receiver is equipped with pressure gauge 25, liquid level gauge 26, a pressure relief pipe 27 controlled by a valve 28. A distillate draw-off line 29 from this receiver controlled by a valve 30 is connected to two leads 31 and 32 controlled by valves 33 and 34:, one leading to storage and the other, the line 31, furnishing means for directing the distillate back through a pump 35 to the charging line 36. In the line 31 are interposed valves 37 and 38. Subsequent to being topped, the liquid oil from the expansion chamber 18 may be drawn oil through a line 39 controlled by a valve 40 through which it may be directed to the line 31, thence to charging line 36 or may be diverted from 1% the system through the pipe 41 regulated by a valve 42.

From any convenient source (not shown) raw oil, such as gas oil, fuel oil, or the like, of a similar nature may be charged to the system by means of pump 43 through the chargIing line 36 controlled by valves 44 and condensate and raw oil charge are pumped,

he oil thus charged is introduced directly to the vapor space in the dephlegmator and after being circulated in an opposed direction to the course of the rising vapors and assisting in their rectification, the combined condensate and charging stock are drawn off through the reflux line 46 and forced through the pump 47 to the heating tubes 1 through the inlet line 48. A valve, 49 controls the flow of reflux and charging oil supply to the pump and directed to the heating tubes for treatment. The operation of the process is obvious from the description of the drawing so that a brief disclosure will suffice.

As explained, the raw oil, such as gas, fuel oil, or oils of a similar character, are charged through the line 36 to the top of the dephlegmator where after intimately intermingling with the cracked oil vapors, the combined to the heating coils Where they are raised to a cracking temperature. The cracked oil is then directed to the vapor or expansion chamher 4 where the released vapors pass off to the dephlegmator and are there subjected to the dephlegmating or rectifying effect of intimate contact with the raw oil charge and indirect contact with the cool crude oil which issupplied to the line 14 and courses through the vertical tubes positioned centrally in the dephlegmator. By this combined means of rectification a very satisfactory dephlegmation of the generated vapors may be obtained. The uncondensed vapors then pass ofi' through the vapor line 50 to a water condenser 51, the final condensate being collected in a receiver 52 connected thereto. The receiver 52 is equipped with the usual regulating devices such as a pressure gauge, a liquid level gauge together with a pressure relief and liquid draw-off means. The crude oil, which is heated in the dephlegmator, acquiring sufficient heat to besubstantially topped, is directed from the bottom chamber 13 to the insulated expansion chamber 18. As previously described, the distillate, after being dephlegmated in the aerial condenser 21 and subjected to a final condensation, is collected in the receiver 24. From this receiver, the distillate may be drawn out of the system or, if desired, may be directed back to the charging line and combined with the raw oil charge which is to be treated in the cracking system. The liquid oil, resulting from the topping in the expansion chamber 18, is likewise either returned with the charging stock to the cracking system or may be diverted as explained through the line 41. It

is a recognized fact that there is not suflicient raw oil fed into the dephlegmator or other rectifier in the usual process to absorb the proper heat energy to properly dephlegmate the generated vapors in a cracking process. For this reason with the addition of comparatively cool crude oil, the quantity of which may be positively controlled, a great amount'of the heat energy necessary to be relieved from the oil vapors in the dephlegmator may be absorbed at the same time raising the temperature of the crude oil to a point where it may be substantially topped. In this manner the heat energy absorbed in the dephlegmating of the oil vapors is efficiently and economically used in the topping of the crude. I

Another important feature is the returning of the cuts from both the topping receiver and the topping expansion chamber which supply heated fractions readily convertible in the cracking system.

Another factor of importance is the accurate regulation which may be obtained by controlling the quantities of crude oil and charging stock used in the dephlegmation of the vapors. Heretofore, atmospheric conditions have been an important factor in the dephlegmation of the vapors and due to the variable charactergof this factor difficulties have been encountered in procuring at all times a. uniform distillate. The present processfurnishes a means forobviating to a great extent this difficulty. The conditions of operation would be approximately as follows Assuming the heating of a charging stock of fuel oil, having a gravity of approximately 25 B. and heating the same in the heating zone to 825 F. and a pressure of from 130 to 150 pounds maintained thereon and a temperature of 750 F. and 130 pounds pressure in the expansion chamber with a similar pressure and a temperature of from 450500 F. in the dephlegmator, fifty to fifty-five per cent of the charge may be obtained as distillate having a gravity of approximately 52 B. Assuming the crude to be introduced at approximately 65-70" F. in regulated quantities, it would be raised to 400-425 F. or thereabouts in the dephlegmator. The insulated expansion chamber in which the topping takes place would have a temperature of substantially 425 F. with a pressure ranging between atmospheric and fifty pounds. The character of the distillate obtained from topping would depend upon the temperature and pressure maintained in the topping expansion chamber. This distillate would range between 3065 B. gravity.

I claim as my invention:

1. The process of treating oil, consisting in passing oil through a cracking zone to subject it to cracking conditions of temperature and superatmospheric pressure to produce substantial vaporization, in discharging the vapors into a dephlegmator, in passing crude petroleum through said dephlegmator out of direct physical contact with the vapors to absorb heat from the vapors, in passing the heated crude oil from the dephlegmator to an expansion chamber where the lighter constituents of the crude oil distill off, in dis-- charging said vaporized constituents to a condenser, and in condensing and collecting the same, introducing raw charging stock to the dephlegmator in direct physical contact with the vapors, and passing reflux condensate and unvaporized charging stock from the dephlegmator to the cracking zone for further treatment.

2. A process for cracking hydrocarbon oil, consisting in subjecting the oil to cracking conditions of heat and pressure to cause substantial conversion thereof, in passing vapors evolved from the oil to a dephlegmator, in introducing a stream of oil, containing consituents readily vaporizable at the temperature maintained in the dephlegmator, to the dephlegmator, in causing such stream of oil to flow through the dephlcgmator out of physical contact with the vapors therein, in then releasing from such oil those constituents vaporizable at the temperature imparted to the oil by its passage through the dephlegs mator and in returning the unvaporized constituents only of such oil to the dephlegmator, and in causing such constituents to flow through the dephlegmator in physical contact with the vapors therein.

3. A process for treating hydrocarbon oil, consisting in raising the oil to a cracking temperature in a heating zone to cause substantial conversion thereof, in passing vapors evolved from the oil to a dephlegmator, in supplying oil to the dephleginator, containing a substantial quantity of constituents vaporizable under the temperature conditions maintained in the dephlegmator, in causing such oil to flow through the dephlegmator out of physical contact with the vapors therein, in relieving from such oil such constituents as have been vaporized by the heat imparted thereto, in re-passing the unvaporized portions only of such oil through the dephlegmator in physical contact with the vapors therein, in withdrawing such oil, subsequent to its passage to the dephlegmator in physical contact with the vapors therein, together with reflux condensate separated from the vapors in the dephlegmator and in supplying such withdrawn oil to said heating zone, and in maintaining a superatmospheric pressure on the oil in the. heating zone and the vapors undergoing dephlegmation.

4. In a cracking'apparatus, means where by hydrocarbons are cracked and vaporized, a reflux condenser wherein high boiling point fractions are condensed, said reflux condenser including a heat exchanger wherein charging stock is preheated while out of contact with the vapors, regulating means to.

fractions are condensed, said reflux condenser including a heat exchanger wherein charging stock is preheated while out of contact with the vapors, regulating means to control the delivery of charging stock through said heat exchanger so as to regulate the vapor temperature therein, a conductor through which preheated charging stock is admitted to the vapor space in said reflux condenser, and regulating means to control the flow through saideonductor irrespective of rate of flow through said heat exchanger, said regulating means being adjustable independently of each other, and the outlet of said heat exchanger being provided with a discharge conduit for the surplus charging stock.

6. In a cracking apparatus, means whereby hydrocarbons are cracked and vaporized, a reflux condenser wherein high boiling point fractions are condensed, said reflux condenser including a heat exchanger wherein charging stock is preheated while out of contact with the vapors, regulating means to control the delivery of charging stock through said heat exchanger so as to regulate the vapor temperature therein, a conductor through which preheated charging stock from said heat exchanger is admitted to the vapor space in said reflux condenser, means for introducing additional oil to said conductor, and regulating means to control the flow through said conductor irrespective of rate of flow through said heat exchanger.

ROBERT T. POLLOCK. 

